If you see the bible, it mainly deals with behaving according to the values mentioned in the religion.
Gita goes further and advocates dismissing all religions to acquire the liberation.
While Bhagwat goes still further and describes the ultimate love bliss by dismissing liberation.
Hence it said the where bible ends, Gita begins and where Gita ends Bhagwat begins.
Bhagwat is also known as paramhans Gita because the audience is Shuk Dev who has already acquired the liberation but then he finds listening to attributes of God with form more entertaining than the joy of liberation. Both liberation and love bliss are divine, meaning eternal and infinite but the love bliss is something special because of which Shuk Dev selected God with form over liberation.
Gita begins with Arun who was ingorant and ends with liberation. Bhgwat proclaims that this love nectar is above all deceits of religion, money, sex and liberation.
Therefore Bhgavat is the best devotional scripture. It is the fifth Ved. It is the meaning and essence of ved as claimed by the writer of Ved- Ved Vyas himself.